The present invention relates to a low power consumption electronic circuit, and more particularly to a low power consumption electronic circuit which is operated by the voltage of a battery.
An electronic circuit such as an electronic watch to be driven by a battery is required to be of low power consumption with a view for elongating the lifetime of the battery.
Generally speaking, a circuit such as an electronic circuit (which will be shortly referred to as an "CMOS circuit"), which is constructed of complementary type insulated gate field effect transistors, can have its current consumption reduced by dropping the power supply voltage to be impressed thereon.
Consequently, the power to be consumed by an electronic circuit as a whole can be reduced by operating the circuit not with the power supply voltage, which is directly supplied from the battery, but with such a power supply voltage at a relatively low level as is fed out of a low current consumption type voltage regulator itself, for example.
In the above case, however, between the input and output terminals of the voltage regulator, there appears a voltage at such a level as is equal to the difference between the battery voltage and the power supply voltage supplied to the electronic circuit, and there flows a current which is substantially equal to that consumed in the electronic circuit.
As a result, a relatively high power consumption takes place in the voltage regulator.
On the other hand, the current to be fed out of the battery is reduced substantially to an extent equal to the reduction in the current consumed by the electronic circuit. As a result, it is difficult to remarkably elongate the lifetime of the battery.